Can I use Druid union datasources in plyql, plywood and/or pivot queries?

Druid guru’s,

I’ve successfully exercised the union datasource in a druid query sent directly to the broker.

I’d really like to use this functionality from some of the higher level interfaces (plyql, plywood API from node, and from pivot UI).

Is this possible?

If so, how?

Cheers,

Paul